Fluid absorber for a suction tube. set

ABSTRACT

The suction tube set employs a compressed cellulosic sponge mass as a fluid absorber in the suction line for absorbing an amount of fluid, for example 1.5 cc, without any significant increase in resistance to air flow. The compressed sponge mass is secured in place within a tubular housing of the suction tube set with a gap formed between each end of the sponge mass and an end cap of the housing to avoid blockage of air flow.

[0001] This application is a division of Ser. No. 09/326,269, filed Jun.7, 1999.

[0002] This invention relates to a fluid absorber for a suction tubeset. More particularly, this invention relates to a fluid absorber for asuction tube set for use in laser eye surgery.

[0003] As is known, various types of devices and equipment have beenutilized in surgical procedures performed on an eyeball and particularlyfor photoretractive keratectomy laser surgery. During such procedures, aweak laser beam is used to remove tiny layers of tissue and to reshapethe cornea to improve sight. Typically, photoretractive keratectomy isaccomplished by an excimer laser beam that ablates away corneal tissuein a photodecomposition process. Before this occurs, a flap of theepithelium of the cornea is surgically removed to expose Bowman's layeron the anterior surface of the stroma. The excimer laser beam is thenused for laser ablation at Bowman's layer. The laser beam is also usedto remove corneal tissue to varying depths as necessary forre-contouring the anterior stroma. Afterward, the epithelium flap isrepositioned to rapidly regrow and resurface the contoured area.

[0004] In order to stabilize an eyeball for purposes of such a surgicallaser operation, it has been known to fix the eyeball in place using asuction device. This allows a surgeon to operate on the eyeball withoutthe risk that the eyeball may move during the operation.

[0005] One known device for stabilizing an eyeball and for effectingremoval of an epithelium flap is an automated disposable keratome soldby LaserSight Technologies, Inc. of Winter Park, Fla. This instrumentprovides a ring which is to be placed on the eyeball as well as akeratome for slicing a flap in the epithelium of the eyeball. Once thering is in place with suction on, the keratome can be operated by asurgeon to cut the flap. High suction is generally required briefly toraise the LOP (intraocular pressure) and keep the eye rigid so that aclean cut can be made. However, there is a danger involved with suchinstruments if there is a loss of suction during this cutting time.Accordingly, the instrument is provided with an alarm that warns asurgeon instantly if suction is lost.

[0006] Studies have shown that the IOP rises to over 99 mmHg at maximumsuction, with the estimated actual IOP during maximum suction being ashigh as 130 or 140 mmHg. However, prolonged exposure to this level ofIOP creates a potential for damage to delicate retinal structures. Thus,in order to preclude damage, the time of exposure to high vacuum islimited to an absolute minimum.

[0007] Thus, with the suction ring in place and the vacuum set at 5inches of mercury (Hg), the patient's IOP rises to the 30-35 mmHg range.This relatively safe level of vacuum is enough to hold the ring in placebut not enough to produce a good cut. So when the surgeon activates thekeratome, the vacuum rises immediately to 24 inches of mercury, pushingthe IOP high enough for a good cut. However, the high vacuum lasts onlyfor the 2 to 3 seconds required for the keratome to go forward acrossthe ring. When the keratome goes back, the vacuum drops down again to 5inches Hg, enough to hold the ring in place but not enough to endangerthe retina and optic nerve.

[0008] Another problem which arises during an eye operation of the abovetype is due to the fact that tearing of the eyeball usually occurs sothat fluid, i.e. salt water, is drawn into the suction ring andeventually into the vacuum pump. Should fluid begin to enter the vacuumpump, the pump can cease to draw a vacuum so that the eyeball is nolonger locked in place. This is particularly the case where the pumpretains fluid from a succession of eye operations.

[0009] In order to prevent fluids from migrating into the vacuum pump,fluid traps have been incorporated in the suction line between thevacuum pump and eyeball-engaging ring. That is to say, the line from thering terminates in a vertically disposed trap to deliver fluid into thetrap while a second line extends from the trap to the vacuum pump inorder to conduct a vacuum force from the vacuum pump. Typically, the twolines are sealed relative to the interior of the trap so that a“reservoir” of fluid can be accumulated within the trap while an airspace is provided above the “reservoir” of fluid to conduct an air flowtherethrough. One of the problems with such a trap is that the trap mustbe maintained vertical as the trap operates under gravity. Accordingly,care must be taken to ensure that the trap does not turn upside down, asotherwise, fluid would immediately pass into the vacuum pump therebyrendering the pump inoperative.

[0010] It has also been known to place filters in the suction tube linesin order to prevent fluid coming from an eyeball to pass onto the vacuumpump. However, one problem associated with this technique is that as theeyeball side of the filter become filled with fluid, the resistance inthe line to air flow increases. Thus, instead of the vacuum rising to 24inches of mercury at the eyeball, a smaller vacuum force is generated atthe ring-eyeball interface with the risk that a good cut in theepithelium may become compromised.

[0011] Another problem which may arise during an operation is that whichis associated with a slight movement of the ring from the eyeballthrough accident or inadvertence which may cause a slight break in thevacuum due to a separation between the ring and the eyeball. Should thisoccur, an alarm would be sounded or visually indicated to the surgeon sothat the ring may be reoriented and re-attached to the eyeball. However,if a filter has been provided in the suction line which has becomefilled with fluid on the eyeball side, the recovery time for thereengaging the ring with the eyeball is prolonged. In such a case, aneyeball movement can occur.

[0012] Accordingly, it is an object of the invention to reduce the riskof interrupting a photoretractive keratectomy laser operation due to aloss of vacuum caused by an accumulation of fluid in a vacuum pump.

[0013] It is another object of the invention to preclude an accumulationof fluid in a vacuum pump for instruments used in photoretractivekeratectomy laser surgery.

[0014] It is another object of the invention to be able to trap fluid ina suction line set for a keratome without significantly increasing theresistance to air flow in the suction line.

[0015] Briefly, the invention provides a fluid absorber for a suctiontube set for a keratome wherein the fluid absorber comprises a hollowhousing for connection at one side to a vacuum pump and for connectionat an opposite side to the keratome and a formed absorbent mass in thehousing for absorbing fluid emanating from an eyeball without increasingthe resistance to air flow at saturation by more than 3 inches ofmercury. Typically, the absorbent mass is a cellulosic sponge mass.

[0016] In addition, the housing has a cap at each end with a spigot toreceive either a suction tube or an inlet tube as the case may be. Inaddition, the fluid absorber includes a pair of spacer tubes, each ofwhich is located between the sponge mass and the respective cap. Thesespacer tubes serve to space the sponge mass away from the spigotopenings in the end caps in order to avoid clogging of the spigots. Inaddition, the spacer tubes serve to compress the sponge masstherebetween. This compression not only expands the sponge mass radiallyto engage against the inner diameter of the housing and close any spacetherebetween but also eliminates any through passage through the cellsof the sponge mass from one end to the other.

[0017] In another embodiment, the sponge mass may be fixedly secured tothe housing, for example by means of an adhesive at each end thereof, inorder to prevent sliding of the sponge mass within the housing under asuction force of the vacuum pump.

[0018] The invention also provides a suction tube set which is comprisedof the fluid absorber, a suction tube connected to one end of thehousing of the fluid absorber for drawing a vacuum force within thehousing and an inlet tube connected to and extending from an oppositeend of the housing of the fluid absorber for conveying a vacuum forcetherethrough.

[0019] The suction tube set is connected to and between an eyepiece forfitting against an eyeball and a vacuum pump for drawing a vacuum at theeyepiece-eyeball junction. For example, the eyepiece may be the ring ofan automated disposable keratome as sold by LaserSight Technologies Inc.of Winter Park, Fla. This ring is sized to engage an eyeball and has aplurality of ports for communicating with a passageway in the inlettube.

[0020] The absorbent mass is particularly characterized in being able toabsorb fluid without increasing the resistance to air flow by no morethan 2 inches to 5 inches of mercury (Hg). The amount of fluid which isabsorbed by the absorbent mass is based upon the expected amount offluid which would be generated during an operation and by the amount ofresistance created by a fluid-filled mass. That is to say, the absorbentmass is characterized in being able to absorb the amount of fluidexpected to be generated during an operation without significantlyincreasing the resistance to air flow through the absorbent mass.

[0021] The purpose of forming a gap between the caps of the housing andthe sponge mass is to avoid the sponge covering over the apertures ofthe respective caps which communicate with the suction line, asotherwise, the resistance to air flow could increase significantlythereby giving a false high value at the vacuum pump to a surgeon thatthe eyeball to which the eyepiece is locked may have become released andmay have moved. In addition, a significant increase in air flowresistance would significantly increase the response time should vacuumbe lost at the eyeball-eyepiece junction. This would also negate asafety pressure differential system at the vacuum pump which wouldnotify the surgeon that vacuum has been lost.

[0022] Where the absorbent mass is a cellulosic sponge mass, it has beenknown to manufacture such sponges with an anti-bacterial agent in orderto prevent the growth of mold and the like. In accordance with theinvention, the cellulosic sponge mass is compressed to squeeze out theantibacterial agent. Further, compression of the sponge mass reduces thechance that there may be a continuous passage through the sponge massfor a flow of fluid. Typically, the sponge mass can be gamma sterilizedto achieve a sterile product.

[0023] Further, it has been found that compression of the cellulosicsponge mass has little effect on the air flow resistance through thesponge mass.

[0024] Typically, the cellulosic sponge mass is hydrophillic and iscommercially available under the trademark OCELLO and is sold by the 3MCompany. Other types of sponge material may be polyurethane,hydrophillic polyethylene and polypropylene.

[0025] These and other objects and advantages of the invention willbecome more apparent from the following detailed description taking inconjunction with the accompanying drawings wherein:

[0026] FIG. I illustrates a broken view of the fluid absorberconstructed in accordance with the invention;

[0027]FIG. 2 illustrates a cross-sectional view of the absorbent masswithin the housing of the fluid absorber;

[0028]FIG. 3 illustrates an exploded view of the fluid absorber of FIG.1;

[0029]FIG. 4 illustrates a schematic view of the suction tube setincorporating the fluid absorber and connected to an eyepiece at one endand to a vacuum pump at an opposite end;

[0030]FIG. 5 illustrates a perspective view of the eyepiece; and

[0031]FIG. 6 illustrates an end view of the eyepiece.

[0032] Referring to FIG. 1, the fluid absorber 10 is comprised of ahollowed housing 11 of tubular shape and a formed absorbent mass, suchas a compressed cellulosic sponge mass 12 in the housing 11 forabsorbing a fluid volume. As shown in FIG. 4, a suction tube 13 isconnected to one end of the fluid absorber 10 for drawing a vacuum forcewithin the housing 11 and an inlet tube 14 is connected to and extendsfrom an opposite end of the fluid absorber 10 for conveying a vacuumforce therethrough. The resulting suction tube set typically has alength of about 7 feet and is intended to be disposed of after a singleuse.

[0033] Referring to FIGS. 1 and 2 the housing 11 is constructed of anopen end tube or barrel 15, for example, of clear, plastic material. Byway of example, the barrel 15 has an inside diameter of 0.730 inches anda length of 1.5 inches.

[0034] As shown in FIGS. 1 and 3, the housing 11 also has an end cap 16secured to one end of the barrel 15 and a second end cap 17 secured tothe barrel 15 at the opposite end. Each end cap 16, 17 includes an outerrim 18 and an inner rim 19 to define a circumferential recess into whichthe barrel 15 fits. In addition, each end cap 16, 17 has a coaxialspigot 20, 21 extending on an opposite side from the rims 18, 19. Eachend cap 16, 17 also has a hollow stem 22 facing inwardly of the barrel15 which is of axial extent equal to the axial length of the inner rim19 of the end cap 17.

[0035] Each end cap 16, 17 is sized so that the barrel 15 is slidablymounted on the outside diameter of the inner rim 19 of each. A suitableadhesive is also provided to secure each end cap 16, 17 to the surfaceof the barrel 15. By way of example, the adhesive may be a Loctite U.V.adhesive 3311-300 cP.

[0036] The spigot 20, 21 of each end cap 16, 17 is slightly tapered in aconventional manner to receive the respective tube 13, 14, as indicatedin FIG. 4.

[0037] The sponge mass 12 is disposed within the barrel 15. In addition,a pair of spacer tubes 23 are disposed within the housing 11 with eachtube 23 being disposed between the sponge mass 12 and a respective endcap 16, 17. During assembly, the sponge mass 12 is first placed withinthe barrel 15 as indicated in FIG. 2. Thereafter, as indicated in FIG.3, a pair of spacer tubes 23 and the end caps 16, 17 are moved into andover the ends of the barrel 15. During this time, the spacer tubes 23compress the sponge mass 12. As a result, the sponge mass 12 islongitudinally compressed while being radially expanded against theinner periphery of the barrel 15. The result is that any throughpassageway through the sponge mass 12 is broken up and eliminated and,at the same time, the sponge mass 12 is sealed against the innerperiphery of the barrel 15 so that there are no pathways formed betweenthe sponge mass 12 and the barrel 15.

[0038] The sponge mass 12 is formed, for example, by four coaxiallydisposed sections of sponge material which are compressed when assembledinto the barrel 15.

[0039] The fluid absorber 10 in the suction tube set serves to absorbfluid (tears) passing to the absorber without increasing the resistancesto air flow at saturation by more than 3 inches Hg.

[0040] Once assembled, the fluid absorber 10 is fitted with the suctiontube 13 and inlet tube 14. The suction tube 13 may also be fitted with aconnector of conventional structure, such as a Colder-DSM-2202, forconnection to a vacuum pump 24 (see FIG. 4) in a conventional manner. Inaddition, the inlet tube 14 is connected to a keratome instrument 25.

[0041] Typically, the suction tube 13 is made of polyvinylchloridehaving dimensions of ¼″×⅛″×4″. The inlet tube 14 is similarly made ofpolyvinylchloride with dimensions of {fraction (3/16)}″×⅛″×84″. Theoverall length of the two tubes 13, 14 is seven feet.

[0042] The sponge pieces employed within the housing 11 each have aninitial uncompressed thickness of ⅝″ and an outside diameter of ¾″. Inthe compressed state, the axial length of the sponge mass 12 is slightlyless than the axial length of the barrel 15 i.e. slightly less than1.5″. Thus, the four sponge pieces are reduced from an overall length of2.5″ to about half of that length.

[0043] Referring to FIG. 5, the keratome 25 is constructed, as is known,for fitting against an eyeball 26 and is typically provided with an endring 27 of curved contour having a plurality of circumferentiallydisposed ports 28 through which air can be drawn. (See FIG. 6). Theseports 28 are thus in communication with a passageway in the inlet line14.

[0044] When a surgeon is to operate on the eyeball of a patient, the endring 27 of the eyepiece 25 is brought into contact with the eyeball 26and vacuum drawn on the eyepiece 25 so that the suction force effectedthrough the ports 28 in the end ring 27 of the eyepiece 25 locks theeyeball 26 and end ring 27 together. Thus, the surgeon is able toperform a surgical procedure on the eyeball 26 on the assumption thatthe eyeball will remain fixed in place. For example, in the case of anautomated disposable keratome, as noted above, a blade (not shown) maybe activated to effect the slicing of a flap in the epithelial layer ofthe eyeball. Thereafter, use is made of a laser beam to ablate cornealtissue.

[0045] Typically, a low vacuum pressure, for example at 8″ or less ofmercury (Hg) is used to lock the eyepiece 25 to the eyeball. The lockingeffect takes place over milliseconds.

[0046] As tearing occurs during the surgical procedure, any fluid, i.e.salt water, emanating from the eyeball 26 into the end ring 27 via theports 28 migrate down the inlet tube 14 and eventually into the fluidabsorber 10. The compressed cellulosic sponge mass 12 of the absorber 10will then absorb the fluid volume. For example, a typical surgicalprocedure will produce up to 0.5 cubic centimeters of fluid. The spongemass 12 has a capacity of absorbing 1.5 cubic centimeters of fluidthereby providing an adequate safety factor while providing a minimalresistance to air flow so that the vacuum pump 26 is able to continue tooperate at the vacuum pressure of 24 inches of mercury (Hg). Uponsaturation of the compressed sponge mass 12, resistance to air flowincreases slightly.

[0047] The capacity of the sponge mass 12 to absorb fluid without asignificant increase in resistance to air flow allows a surgicalprocedure to continue under normal conditions. Typically, the amount offluid to be adsorbed by the compressed sponge mass 12 is less than thatwhich is reasonably expected during a surgical procedure.

[0048] The invention thus provides a disposable fluid absorber forabsorbing a fluid volume within a suction tube set used with a keratomefor laser eye surgery without significant increase in resistance to airflow.

[0049] The fluid absorber may be employed without regard to a verticalor horizontal disposition as the forces of gravity are not of anyconsequence in the functionality of the absorber.

[0050] While the sponge mass 12 has been described as a compressedcellulosic sponge mass, it is understood that other types of materialsmay also be used provided the materials satisfy the characteristic ofabsorbing an amount of fluid while increasing the resistance to air flowat saturation by only a small amount.

[0051] The suction tube set is characterized by having a low inherentpressure drop. When disconnected with the one end free and exposed tothe room, the vacuum created at the entrance to the vacuum pump isapproximately 7-8 inches of mercury. When connected to the eyepiece andthere is no air leakage into the system, the vacuum pump will typicallydraw 26 inches plus of mercury.

[0052] A unique characteristic of this suction tube set is the abilityto absorb quantities of a person's tears (salt water) with little changein resistance to air flow. Hence, after the fluid absorber has absorbede.g. ½ cc of tears, the open line will still exhibit a vacuum of 8-10inches of mercury.

[0053] This condition provides two advantages over suction linescontaining filter traps which are generally the system of choice due totheir inherent nature of positively preventing fluid from entering thevacuum pump and thereby destroying it's ability to continue to function.The first advantage is that the fluid absorber may absorb quantities oftears with minimal increase in resistance to air flow. The secondadvantage is the inherent low resistance to flow of the system.

[0054] The results of these advantages are the laser equipment can beprogrammed such that when resistance (negative pressure) at the vacuumpump inlet drops due to loss of suction at the connection between theeyeball 26 and suction ring 27, it will become immediately evident for alow vacuum pressure (below 15 inches of mercury) will instantaneouslyappear at the entrance to the vacuum pump. This pressure sensitivity canbe translated into a signal which can inform the practitioner or whenconnected to the laser (surgical knife) will immediately shut the systemdown before harm can occur to the person's eye due to potential eyemovement. (Improper cutting, cutting in the wrong area, etc.) The secondadvantage is that vacuum recovery when suction is lost due to leakagebetween the suction ring 27 and the eyeball 26 is significantly fasterthan suction systems using lower air flow due to higher line resistance.This reduces the likelihood of improper cutting or otherwise causingthis medical procedure to result in poorer results than expected.

What is claimed is:
 1. A fluid absorber for a suction tube set for akeratome, said fluid absorber comprising a hollow housing for connectionat one side to a vacuum pump and for connection at an opposite side to akeratome; and a formed absorbent mass in said housing for absorbing afluid without increasing the resistance to air flow at saturation bymore than 3 inches of mercury.
 2. A fluid absorber as set forth in claim1 wherein said absorbent mass is a cellulosic sponge mass.
 3. A fluidabsorber as set forth in claim 2 wherein said housing has a first cap atone end with a spigot to receive a suction tube and a second cap/at theopposite end with a spigot to receive an inlet tube and which furthercomprises a first spacer tube between said sponge mass and said firstcap and a second spacer tube between said sponge mass and said secondcap.
 4. A fluid absorber as set forth in claim 3 wherein said spongemass is compressed by and between said spacer tubes.
 5. A suction tubeset comprising a hollowed housing of tubular shape; a formed absorbentmass in said housing for absorbing a fluid; a suction tube connected toone end of said housing for drawing a vacuum force within said housing;and an inlet tube connected to and extending from an opposite end ofsaid housing for conveying a vacuum force therethrough.
 6. A suctiontube set as set forth in claim 5 wherein said absorbent mass is acompressed sponge mass.
 7. A suction tube set as set forth in claim 6wherein said compressed sponge mass is characterized in absorbing nomore than 1.5 cubic centimeters of fluid.
 8. A suction tube set as setforth in claim 6 wherein said compressed sponge mass is formed of aplurality of axially disposed layers.
 9. A suction tube set as set forthin claim 7 wherein said housing has a first cap at one end with a spigotreceiving said suction tube, and a second cap at an opposite end with aspigot receiving said inlet tube.
 10. A suction tube set as set forth inclaim 9 which further comprises a first spacer tube between saidcompressed sponge mass and said first cap and a second spacer tubebetween said compressed sponge mass and said second cap.
 11. A suctiontube set as set forth in claim 9 wherein said housing has a tubularbarrel secured to and between said caps.
 12. A suction tube set as setforth in claim 11 wherein said barrel is made of a thin transparentplastic.
 13. A suction tube set as set forth in claim 5 wherein saidmass is spaced from said first cap to define a gap therebetween and isspaced from said second cap to define a gap therebetween.
 14. A suctiontube set as set forth in claim 13 wherein said mass is secured in saidhousing at each of two opposite ends thereof to prevent movement of saidmass within said housing against said end caps.
 15. A suction tube setcomprising a housing having a first spigot at one end and a secondspigot at an opposite end; a suction tube mounted on said first spigotof said housing to draw a suction force within said housing; an inlettube mounted on said second spigot of said housing to convey a suctionforce therethrough; and a formed absorbent mass in said housing forabsorbing a fluid volume passing through said housing from said inlettube without increasing the resistance to air flow at saturation by morethan 3 inches of mercury.
 16. A suction tube set as set forth in claim15 wherein said formed absorbent mass has a capacity to absorb 1.5 cubiccentimeters of fluid.
 17. A suction tube set as set forth in claim 15wherein said absorbent mass is formed of a plurality of coaxiallydisposed layers of compressed cellulosic sponge.